LEC - 7.2 - Beta & Calcium Blockers Flashcards
Location of Beta Receptors:
Heart (stimulation)
Bronchial, uterine, and vascular smooth muscle (relaxation)
Adipose tissue (lipolysis)
2 types of Beta Blockers:
Nonselective
Cardioselective
These drugs have similar antihypertensive effects irrespective of additional properties
Inhibit the secretion of renin and the formation of angiotensin I
Beta Adrenergic Blockers
Therapeutic applications of Beta Blockers
decreases cardiac workload and can ease the symptoms of angina pectoris. By slowing conduction through the mycardium, they treat dysrhythmias. They are also included in the treatment of heart failure, MI and migraine.
These beta blockers block both beta1 and beta2 receptors and so affect the heart, lungs, vascular smooth muscles, kidneys, GI, etc
Nonselective Beta Blockers
These bete blockers work by blocking beta-1 receptors, which prevents epinephrine from binding to these receptors. As a result, these medications block the effects of epinephrine, also known as adrenaline, in order to decrease heart rate and the contractility of the heart
Cardioselective Beta Blockers
Examples of Nonselective Beta Blockers:
ropranolol
nadolol
timolol
pindolol
labetolol
carvedilol
Examples of Cardioselective Beta Blockers:
metoprolol
atenolol
esmolol
betaxolol
Non Cardiovascular Uses for Beta Blockers:
Migraine
In anxiety provoking situations
Glaucoma
Hyperthyroidism
Pheocromocytoma
Alcohol withdrawal
Oesophageal varices
Advantages of Beta Blockers
No postural hypotension
No salt and water retention
Low incidence of side effects
Low cost
Once a day regimen
Preferred in young non-obese patients, prevention of sudden cardiac death in post infarction patients and progression of CHF
Side effects of Beta Blockers:
Fatigue, lethargy or decreased work capacity
Loss of libido or impotence
Cognitive defects like forgetfulness
Adverse effects of Beta Blockers:
Bronchoconstriction
Bradycardia
Cold extremeties
CNS side effects
Heart Failure
Hypoglycemia
Rebound hypertension
Advantages of cardio-selective over non-selective:
Safe for use in:
Asthma
Diabetes mellitus
Peripheral vascular disease
Preferred in young non-obese hypertensive
Angina pectoris and post angina patients
Post MI patients – useful in preventing mortality
In old persons, carvedilol, which has a vasodilatory action can be given
Lowers BP directly by blocking the sympathetic receptor in arterioles causing the vessels to dilate
Alpha Adrenergic Blockers
These drugs are not the first-line drugs for HTN because long-term clinical trials have shown them to be less effective at reducing the incidence of serious cardiovascular events than diuretics.
Alpha Adrenergic Blockers
Non selective alpha blockers like ___ and ___ are not used in chronic essential hypertension but only in pheochromocytoma (vascular tumor of chromaffin tissue of the adrenal medulla).
phenoxybenzamine and phentolamine
Non selective alpha blockers like phenoxybenzamine and phentolamine are not used in chronic essential hypertension but only in ___ (vascular tumor of chromaffin tissue of the adrenal medulla).
pheochromocytoma
vascular tumor of chromaffin tissue of the adrenal medulla
pheochromocytoma
Specific alpha-1 blockers like ___, ___, and ___ are used in chronic essential hypertension
prazosin, terazosin and doxazosine
Specific alpha-1 blockers like prazosin, terazosin and doxazosine are used in ___
chronic essential hypertension
___ is effective against benign prostatic hypertrophy (BPH)
Tamsulosin
Tamsulosin is effective against ___
benign prostatic hypertrophy (BPH)
Therapeutic Uses of Alpa-Blockers:
Reduction in mean BP
Does not produce tachycardia since presynaptic auto or alpha-2 receptors are not inhibited
Autoregulation of Na+ release remains intact
Adverse effects of Alpa-Blockers:
Prazosin causes postural hypotension so start with 0.5 mg at bed time with increasing dose and up to 10 mg daily
Fluid retention in monotherapy
Headache, dry mouth, weakness, blurred vision, rash, drowsiness and failure of ejaculation in males
___ causes postural hypotension so start with 0.5 mg at bed time with increasing dose and up to 10 mg daily
Prazosin
Prazosin causes postural hypotension so start with ___ mg at bed time with increasing dose and up to ___ mg daily
0.5
10
Current status of Alpa-Blockers:
Improvement of carbohydrate metabolism so beneficial for diabetics since it lowers LDL and increases HDL
Not used as first line agent
Used in addition with other conventional drugs which are failing such as diuretic or beta blocker
Other example:
Minipress
Prazopress
these drugs prevent the movement of calcium into the cardiac and smooth muscle cells when the cells are stimulated
Blocking of calcium interferes with the muscle cell’s ability to contract, leading to a loss of smooth muscle tone, vasodilation, and a decrease in peripheral resistance
Calcium Channel Blockers
Calcium channel blockers are effective in the treatment of ___
angina
Examples of Calcium Channel Blockers available in the Philippines:
Amlodipine (Norvasc)
Felodipine (Plendil ER)
Nifedipine ( Adalat, Calcibloc)
Diltiazem ( Dilzem)
Nicardipine (Cardepine)
Potential Side Effects of Calcium Blockers:
Dizziness or lightheadedness
Low blood pressure
Heart rhythm problems
Dry mouth
Edema (swelling of ankles, feet, or lower legs)
Headache
Potential Side Effects of Calcium Blockers:
Nausea
Fatigue
Skin rash
Constipation or diarrhea
Gastroesophageal reflux disease
Advantages of Calcium Blockers:
Unlike with diuretics, there is no adverse metabolic effects but mild adverse effects like dizziness, fatigue, etc.
No sedation or CNS effect
Can be given to asthma, angina and PVD patients
No renal and male sexual function impairment
No adverse fetal effects and can be given in pregnancy
Minimal effect on quality of life
CCBs are not 1st line of antihypertensive unless indicated but rather the use of ACE Inhibitors/diuretics/beta blockers. However it is been used because of excellent tolerability and high efficacy
NA
Preferred in elderly because it prevents stroke
Calcium Channel Blockers
CCBs are next to ACE inhibitors in inhibition of ___ and prevention of ___
albuminuria
diabetic nephropathy
CCBs nteract with ___ causing an increase level of calcium channel blockers to toxic dose
grapefruit juice
